When multiple resonators are allowed to influence one another coupling interactions take place, which can often be complex and difficult to model. Understanding how these interactions depend on the shapes, sizes and positions of resonators has allowed scientists and engineers to design devices with exotic and remarkable properties. Some notable examples include effectively negative material parameters [1]}, [2]}, cloaking devices [3]}, [4]} and bio-inspired structural colouration [5]}, [6]}. The word metamaterial is a broad term that is often used as a catchall term to encompass materials whose emergent properties arise due to geometry and structure (as opposed to purely from chemistry) [7]}.
